Disposal/Conversion of Waste Hydrogen Gas

[iHydrogen]

Hi All,

I am constructing an electrolyzer test stand that is going to produce small amounts (< 1 kg/hr) of hydrogen gas. Because of space requirements at my facility, this electrolyzer cannot be situated close enough to an appropriate vent or hood to release the gas into the atmosphere. I have never had this problem before, so I am looking for suggestions on how to safely and inexpensively convert or burn this waste gas.

The hydrogen will be relatively pure, greater than 99% purity, and pressure will be ambient (~1 atm). Flow will be relatively constant, however brief periods of turn down can be expected (so a fuel cell will probably be tough to implement). I've looked into catalytic recombiners but all I could find were ones for nuclear power plants... much larger and more expensive than the <1 kg/hr capacity I am dealing with here.

Any help is greatly appreciated.

 

[StoneCold]

When I worked at a Semiconductor facility we had little glow plugs that ignited the hydrogen in the vent line, It had an infrared sensor that watched the flame and alarmed if there was a flameout. Maybe that would work for you. You could just vent it into the room as long as you had approapriate shutdown interlocks.

Regards
StoneCold

 

[iHydrogen]

Is this something you built yourself or something you bought? I considered building something like that myself, however there are a lot of safety considerations to think about especially since this type of vent stack would need openings for air intake. I'd rather buy something commercially available to take care of this hydrogen.

 

[StoneCold]

They were an integral part of the furnace system.

 

[cheute79]

Years ago I did a lot of work in support of TMI-II cleanup, and one of the tasks was to look into recombiners for waste shipping canisters. I did extensive testing on recombiners over several years. There is nothing magical about them. You could probably make some yourself, or perhaps talk a vendor into providing a sample for free. The generation rate you will have is so small that perhaps 100 g (or less) of recombiner is needed. The cost might be less than $100US. The recombiner is nothing more than (ideally) a single-molecule thick layer of a platinide (or perhaps even any non-oxidized Group VIII element) on a substrate that provides a large surface area/mass. Sintered ceramics are a nice substrate. Create a solution of a platinide salt (paladium chloride?), dip the substrate in the salt and let it dry. Repeat 6-10 times, then put it in a reducing oven at 200-300°C for a short period, cool and rinse. You could also just use a film of platinide. It'll just get hot (when "working" a reaction site can get red-hot).

StoneCold is correct that the recombiners are often a part of the furnace if its a newer one. The generators, whether commercial or made by you, will need a lot of maintenance and attention. Pure H2 is really kind of nasty. It will embrittle the metals and the polymers (hoses and gaskets). It's hard to contain.

 

[dcasto]

how about a fuel cell

http://www.fuelcellstore.com/en/pc/viewPrd.asp?idcategory=36&idproduct=1284

 

[moltenmetal]

As I posted to this previously, your easiest and cheapest and most reliable "recombiner" at these tiny rates will be two Bunsen burners: one running with fuel gas as a pilot, and the other running with your hydrogen. That is, unless you're running a mixed cell generating a hydrogen/oxygen mixture!

You don't want the risk of discharging hydrogen into an improperly ventilated space. Find a way to get a vent line in there.